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	$174.92	9.559%	$191.6406	$191.64	$191.65	$191.60
Purchase #2	$31.98	3.369%	$33.0574	$33.06	$33.05	$33.10
Purchase #3	$156.35	5.253%	$164.5631	$164.56	$164.55	$164.60
Purchase #4	$168.59	3.405%	$174.3305	$174.33	$174.35	$174.30
Purchase #5	$55.58	7.407%	$59.6968	$59.70	$59.70	$59.70
Purchase #6	$168.53	12.386%	$189.4041	$189.40	$189.40	$189.40
Purchase #7	$45.29	9.123%	$49.4218	$49.42	$49.40	$49.40
7 purchase totals =	$801.24		$862.1143	$862.11	$862.10	$862.10