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	$57.54	3.857%	$59.7593	$59.76	$59.75	$59.80
Purchase #2	$103.46	4.599%	$108.2181	$108.22	$108.20	$108.20
Purchase #3	$154.87	3.125%	$159.7097	$159.71	$159.70	$159.70
Purchase #4	$201.47	4.849%	$211.2393	$211.24	$211.25	$211.20
Purchase #5	$145.57	6.300%	$154.7409	$154.74	$154.75	$154.70
Purchase #6	$81.81	11.581%	$91.2844	$91.28	$91.30	$91.30
Purchase #7	$223.43	7.682%	$240.5939	$240.59	$240.60	$240.60
7 purchase totals =	$968.15		$1,025.5456	$1,025.54	$1,025.55	$1,025.50