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	$196.51	4.493%	$205.3392	$205.34	$205.35	$205.30
Purchase #2	$169.33	9.563%	$185.523	$185.52	$185.50	$185.50
Purchase #3	$244.51	4.172%	$254.711	$254.71	$254.70	$254.70
Purchase #4	$180.83	4.842%	$189.5858	$189.59	$189.60	$189.60
Purchase #5	$72.48	6.597%	$77.2615	$77.26	$77.25	$77.30
Purchase #6	$80.31	9.776%	$88.1611	$88.16	$88.15	$88.20
Purchase #7	$144.57	4.487%	$151.0569	$151.06	$151.05	$151.10
7 purchase totals =	$1,088.54		$1,151.6385	$1,151.64	$1,151.60	$1,151.70