Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$236.54	11.324%	$263.3258	$263.33	$263.35	$263.30
Purchase #2	$190.57	12.358%	$214.1206	$214.12	$214.10	$214.10
Purchase #3	$212.44	5.157%	$223.3955	$223.40	$223.40	$223.40
Purchase #4	$112.78	3.114%	$116.292	$116.29	$116.30	$116.30
Purchase #5	$181.35	8.344%	$196.4818	$196.48	$196.50	$196.50
Purchase #6	$167.93	4.275%	$175.109	$175.11	$175.10	$175.10
Purchase #7	$102.53	3.211%	$105.8222	$105.82	$105.80	$105.80
7 purchase totals =	$1,204.14		$1,294.5469	$1,294.55	$1,294.55	$1,294.50