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	$118.89	5.408%	$125.3196	$125.32	$125.30	$125.30
Purchase #2	$96.38	13.488%	$109.3797	$109.38	$109.40	$109.40
Purchase #3	$155.54	4.713%	$162.8706	$162.87	$162.85	$162.90
Purchase #4	$23.64	3.528%	$24.474	$24.47	$24.45	$24.50
Purchase #5	$151.32	9.603%	$165.8513	$165.85	$165.85	$165.90
Purchase #6	$153.70	11.853%	$171.9181	$171.92	$171.90	$171.90
Purchase #7	$243.38	6.196%	$258.4598	$258.46	$258.45	$258.50
7 purchase totals =	$942.85		$1,018.2731	$1,018.27	$1,018.20	$1,018.40