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	$70.40	9.403%	$77.0197	$77.02	$77.00	$77.00
Purchase #2	$78.72	3.753%	$81.6744	$81.67	$81.65	$81.70
Purchase #3	$221.71	11.515%	$247.2399	$247.24	$247.25	$247.20
Purchase #4	$142.53	6.361%	$151.5963	$151.60	$151.60	$151.60
Purchase #5	$54.29	4.799%	$56.8954	$56.90	$56.90	$56.90
Purchase #6	$227.67	11.368%	$253.5515	$253.55	$253.55	$253.60
Purchase #7	$161.51	11.700%	$180.4067	$180.41	$180.40	$180.40
7 purchase totals =	$956.83		$1,048.3839	$1,048.39	$1,048.35	$1,048.40