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	$216.92	7.597%	$233.3994	$233.40	$233.40	$233.40
Purchase #2	$219.71	10.443%	$242.6543	$242.65	$242.65	$242.70
Purchase #3	$168.27	6.440%	$179.1066	$179.11	$179.10	$179.10
Purchase #4	$134.44	6.155%	$142.7148	$142.71	$142.70	$142.70
Purchase #5	$79.68	10.477%	$88.0281	$88.03	$88.05	$88.00
Purchase #6	$135.33	6.811%	$144.5473	$144.55	$144.55	$144.50
Purchase #7	$68.27	6.444%	$72.6693	$72.67	$72.65	$72.70
7 purchase totals =	$1,022.62		$1,103.1198	$1,103.12	$1,103.10	$1,103.10