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	$141.73	7.216%	$151.9572	$151.96	$151.95	$152.00
Purchase #2	$218.69	11.719%	$244.3183	$244.32	$244.30	$244.30
Purchase #3	$171.44	10.113%	$188.7777	$188.78	$188.80	$188.80
Purchase #4	$19.58	7.790%	$21.1053	$21.11	$21.10	$21.10
Purchase #5	$156.27	4.379%	$163.1131	$163.11	$163.10	$163.10
Purchase #6	$110.87	8.668%	$120.4802	$120.48	$120.50	$120.50
Purchase #7	$156.49	9.569%	$171.4645	$171.46	$171.45	$171.50
7 purchase totals =	$975.07		$1,061.2163	$1,061.22	$1,061.20	$1,061.30