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	$174.74	11.656%	$195.1077	$195.11	$195.10	$195.10
Purchase #2	$143.89	8.759%	$156.4933	$156.49	$156.50	$156.50
Purchase #3	$64.95	4.534%	$67.8948	$67.89	$67.90	$67.90
Purchase #4	$61.32	4.448%	$64.0475	$64.05	$64.05	$64.00
Purchase #5	$109.26	6.803%	$116.693	$116.69	$116.70	$116.70
Purchase #6	$222.34	12.362%	$249.8257	$249.83	$249.85	$249.80
Purchase #7	$239.64	9.242%	$261.7875	$261.79	$261.80	$261.80
7 purchase totals =	$1,016.14		$1,111.8495	$1,111.85	$1,111.90	$1,111.80