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	$219.83	11.226%	$244.5081	$244.51	$244.50	$244.50
Purchase #2	$85.27	9.646%	$93.4951	$93.50	$93.50	$93.50
Purchase #3	$100.34	3.869%	$104.2222	$104.22	$104.20	$104.20
Purchase #4	$131.71	9.510%	$144.2356	$144.24	$144.25	$144.20
Purchase #5	$243.81	4.303%	$254.3011	$254.30	$254.30	$254.30
Purchase #6	$92.80	11.809%	$103.7588	$103.76	$103.75	$103.80
Purchase #7	$218.81	3.232%	$225.8819	$225.88	$225.90	$225.90
7 purchase totals =	$1,092.57		$1,170.4028	$1,170.41	$1,170.40	$1,170.40