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	$204.95	4.399%	$213.9658	$213.97	$213.95	$214.00
Purchase #2	$37.89	9.132%	$41.3501	$41.35	$41.35	$41.40
Purchase #3	$79.78	11.706%	$89.119	$89.12	$89.10	$89.10
Purchase #4	$64.69	4.141%	$67.3688	$67.37	$67.35	$67.40
Purchase #5	$126.64	7.424%	$136.0418	$136.04	$136.05	$136.00
Purchase #6	$191.28	4.739%	$200.3448	$200.34	$200.35	$200.30
Purchase #7	$242.89	8.657%	$263.917	$263.92	$263.90	$263.90
7 purchase totals =	$948.12		$1,012.1073	$1,012.11	$1,012.05	$1,012.10