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	$144.82	7.221%	$155.2775	$155.28	$155.30	$155.30
Purchase #2	$111.44	4.811%	$116.8014	$116.80	$116.80	$116.80
Purchase #3	$71.41	9.709%	$78.3432	$78.34	$78.35	$78.30
Purchase #4	$153.73	5.695%	$162.4849	$162.48	$162.50	$162.50
Purchase #5	$91.31	4.465%	$95.387	$95.39	$95.40	$95.40
Purchase #6	$227.27	6.474%	$241.9835	$241.98	$242.00	$242.00
Purchase #7	$162.26	8.169%	$175.515	$175.52	$175.50	$175.50
7 purchase totals =	$962.24		$1,025.7925	$1,025.79	$1,025.85	$1,025.80