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	$168.88	13.648%	$191.9287	$191.93	$191.95	$191.90
Purchase #2	$220.79	6.217%	$234.5165	$234.52	$234.50	$234.50
Purchase #3	$74.49	10.225%	$82.1066	$82.11	$82.10	$82.10
Purchase #4	$57.25	3.415%	$59.2051	$59.21	$59.20	$59.20
Purchase #5	$139.44	9.699%	$152.9643	$152.96	$152.95	$153.00
Purchase #6	$91.84	10.415%	$101.4051	$101.41	$101.40	$101.40
Purchase #7	$188.78	6.293%	$200.6599	$200.66	$200.65	$200.70
7 purchase totals =	$941.47		$1,022.7862	$1,022.80	$1,022.75	$1,022.80