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	$181.33	8.255%	$196.2988	$196.30	$196.30	$196.30
Purchase #2	$18.32	12.114%	$20.5393	$20.54	$20.55	$20.50
Purchase #3	$60.90	8.147%	$65.8615	$65.86	$65.85	$65.90
Purchase #4	$20.37	8.623%	$22.1265	$22.13	$22.15	$22.10
Purchase #5	$238.78	12.827%	$269.4083	$269.41	$269.40	$269.40
Purchase #6	$40.46	4.389%	$42.2358	$42.24	$42.25	$42.20
Purchase #7	$130.88	11.346%	$145.7296	$145.73	$145.75	$145.70
7 purchase totals =	$691.04		$762.1998	$762.21	$762.25	$762.10