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	$213.42	8.179%	$230.8756	$230.88	$230.90	$230.90
Purchase #2	$43.88	4.175%	$45.712	$45.71	$45.70	$45.70
Purchase #3	$235.90	13.802%	$268.4589	$268.46	$268.45	$268.50
Purchase #4	$53.93	5.793%	$57.0542	$57.05	$57.05	$57.10
Purchase #5	$40.78	5.817%	$43.1522	$43.15	$43.15	$43.20
Purchase #6	$152.56	8.432%	$165.4239	$165.42	$165.40	$165.40
Purchase #7	$184.42	8.565%	$200.2156	$200.22	$200.20	$200.20
7 purchase totals =	$924.89		$1,010.8924	$1,010.89	$1,010.85	$1,011.00