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	$158.86	9.338%	$173.6943	$173.69	$173.70	$173.70
Purchase #2	$229.44	9.370%	$250.9385	$250.94	$250.95	$250.90
Purchase #3	$18.28	13.190%	$20.6911	$20.69	$20.70	$20.70
Purchase #4	$106.35	5.575%	$112.279	$112.28	$112.30	$112.30
Purchase #5	$213.59	9.289%	$233.4304	$233.43	$233.45	$233.40
Purchase #6	$63.55	12.140%	$71.265	$71.27	$71.25	$71.30
Purchase #7	$170.41	7.424%	$183.0612	$183.06	$183.05	$183.10
7 purchase totals =	$960.48		$1,045.3595	$1,045.36	$1,045.40	$1,045.40